Apparatus for manufacturing coaxial transmission lines



June 4, 1968 D. N. SEWELL 3,386,147

APPARATUS FOR MANUFACTURING GOAXIAL TRANSMISSION LINES Original FiledJune 5, 1965 2 Sheets-Sheet 1 D. N. SEWELL June 4, 1968 APPARATUS FORMANUFACTURING COAXIAL TRANSMISSION LINES 2 Sheets-Sheet 2 Original FiledJune 5, 1965 United States Patent 4 Claims. (Cl. 129-34) ABSTRAQT OF THEDISCLOSURE Apparatus for forming tabs in a tubular electrical conductorand looking a dielectric pin in position with those tabs includes a twocomponent support that is disposed within the conductor and a piercingstructure (having two opposed and aligned piercing elements) which isdisposed outside the conductor. The support has axially separable matingsurfaces which define two diametrically aligned bores (aligned with thepiercing elements), each bore having a smoothly curved entrance; and twoaxially aligned clinching elements. In operation, the two piercingelements are driven through the conductor into the respective bores toform two aligned apertures, each surrounded by inwardly projecting tabs;a dielectric pin is inserted through the aligned apertures; and thespearpoints of the tabs are then forced into the pin in a securingoperation by the clinching elements.

This application is a division of my copending patent application Ser.No. 460,951, filed June 3, 1965.

This invention relates to coaxial transmission lines and, moreparticularly, to apparatus for manufacturing support arrangements formaintaining two tubular conductors in spaced coaxial relation.

Conventional forms of coaxial transmission lines that comprise a tubularinner conductor disposed within a tubular outer conductor employdielectric spacing devices to maintain the coaxial relation of the twotubular conductors. A conventional type of spacing device is a disc thatis disposed in an undercut section of the inner conductor or isotherwise suitably secured so that substantially the entire outerperiphery of the disc engages the inner surface of the outer conductor.Such a spacing device introduces a substantial amount of dielectricmaterial in the line and compensation must be provided to maintain thedesired electrical characteristics of the transmission line. Anotherconventional type of spacing device is a dielectric pin which involvesless dielectric material and hence less compensation than the discdevice. Conventional assembly techniques of such a spacing deviceinvolve the drilling of holes in the inner conductor into which ceramicor polytetrafluoroethylene pins are inserted and then securing the pinsin place by clamping arrangements inside the inner conductor or byplacing sleeves over the exposed ends of the pins, in order to positioneach pin with an equal amount exposed on either side of the innerconductor. A typical pin arrangement is in groups of three offset fromone another radially by 120 at intervals along the inner conductor asprescribed by mechanical support requirements and electrical wave lengthof the signals to be carried in the line. The necessary electricalcompensation for such pins is typically provided by additional holesdrilled in the inner conductor near a single pin or a group of pins, orby forming depressions near the pins in either the inner or outerconductors. It has also been proposed to compensate each pin assemblyindividually, but heretofore such compensation has been expensive toachieve and it has been diffiice cult to appropriately lock the pins inposition on the inner conductor with such compensation.

Accordingly, it is an object of this invention to provide a novel andimproved apparatus for use in manufacturing a coaxial transmission line.

Another object of the invention is to provide a new and improvedapparatus for use in manufacturing a dielectric support structureassembly for a coaxial transmission line.

A further object of the invention is to provide novel and improvedapparatus for securing a dielectric support member in a coaxialtransmission line structure.

A coaxial line constructed in accordance with the invention includes aninner conductor having secured thereto a plurality of radiallyprojecting dielectric support pins of deformable material. The pinspreferably are angularly offset from one another and are spaced axiallyalong the length of the inner conductor. Each pin is disposed in twodiametrically opposed apertures in the inner conductor and extendsthrough the inner conductor with equal portions projecting from eitherside thereof. Each aperture includes a smoothly curved toroidalcompensation surface that bends inwardly of the conductor wall andterminates in a plurality of prongs, at least one of which adjacent eachaperture is forced into the deformable pin material so that that pin ispositively locked in position. The inner conductor with pins securedthereto is then inserted into the outer conductor to form the coaxialline.

In manufacturing the inner conductor-support pin assembly, the innerconductor is first pierced in a controlled manner to simultaneously formthe smoothly curved toroidal compensating surface and the inwardlyprojecting tabs of desired orientation extending from that surface attwo diametrically opposed points. A dielectric pin of suitabledeformable material, such as polytetrafiuoroethylene, is insertedthrough the two diametrically opposed openings and properly positionedso that the portions projecting from either side of the inner conductorare equal. One or more tabs formed on the inside of the inner conductoradjacent each opening are then forced towards and into the dielectricpin material to secure the pin in position. Preferably, the tabs havespearpoints which are firmly embedded in the pin. This structureprovides simple yet secure locking of the pin against axial movement ineither direction at a point not exposed to high frequency electricalforces.

The apparatus for forming the tabs and locking those tabs in positioninto the dielectric pin, in the preferred embodiment, includes atwo-component support arranged for positioning within the innerconductor; a cooperating outer alignment structure which includes guidesfor piercing elements and which also provides an alignment structure forproperly positioning the dielectric pin relative to the inner conductor;and two opposed piercing ele ments with cooperating drive. The twocomponents of the support are axially separable from a mating surfacewhich is bridged by two aperture defining bores, each of which has asmoothly curved entrance. Initially, the inner conductor is positionedbetween the inner support and the cooperating alignment structure andthe two piercing elements are driven from opposite directions towardsone another as guided by the alignment structure into the aperturedefining bores to pierce the inner conductor at two diametricallyopposed points and form two annular smoothly curved compensationsurfaces, the configuration of which is determined by the entrancesurfaces of the bores. Each compensation surface terminates in aplurality of inwardly projecting tabs each of which preferablyterminates in a spearpoint, After the compensation surfaces and the tabshave been formed, the inner support components are separated so thatthey clear the formed tabs and permit rotation and axial movement of theinner conductor.

The inner support also carries a set of opposed tab clinching elements.One element is mounted on one component of the support and thecooperating element is mounted on the other component so that they aremovable axially toward one another. The cooperating alignment structureincludes a curved support surface located at a predetermined radius withrespect to the axis of the inner conductor. After the inner conductorhas been rotated to clear the aperture defining bores, it is moved.

axially so that a dielectric pin may be inserted through the formedconductor openings and positioned on the support surface in properposition. The pin is aligned with the clinching elements and then theyare moved towards one another to act against the tabs and force theirspearpoints into the dielectric pin from opposite sides thereof and ateach opening to securely lock the pin relative to the inner conductor.

The conductor with the locked pin secured therein is then moved toanother desired position relative to the support and cooperatingalignment structure. Other pins are similarly locked to the innerconductor along the length thereof at differingangular positions andthen the assembly of inner conductor and dielectric support pins isinserted into the outer conductor to provide a coaxial transmission linewith the locked dielectric pins supporting and maintaining the desiredcoaxial relationship.

The resulting transmission line has its inner and outer conductorsaccurately supported in coaxial relation by a support structure thatemploys a minimum of dielectric material so that a minimum amount ofcompensation is required, which compensation was formed during theassembly of the support pins. The pins are locked in place in a mannerwhich does not increase the weight of the coaxial line. A furtheradvantage is that no potential sources of contamination such assoldering or welding fluxes are employed in the manufacture of thesupport structure for the coaxial line.

Other objects, features and advantages will be seen as the followingdescription of a particular embodiment of the invention progresses, inconjunction with the drawings, in which:

FIG. 1 is a side view, partially in section, of a coaxial electricaltransmission line constructed in accordance with the invention;

FIG. 2 is a sectional view of the transmission line taken along line 22of FIG. 1;

FIG. 3 is a perspective view of the inner conductor with a series ofdielectric pins secured thereto;

FIG. 4 is a diagrammatic view of apparatus for securing a dielectric pinto the inner conductor;

FIG. 5 is an end View of the apparatus shown in FIG. 4 showing detailsof the piercing device;

FIG. 6 is a perspective view of the inner support employed in theapparatus shown in FIG. 4;

FIGS. 7-10 are diagrammatic views illustrating the series of stepspracticed by the apparatus shown in FIGS. 4-6 for piercing the innerconductor and securing the dielectric pin in place (FIG. 10 being takenalong the line 10-10 of FIG. 13);

FIG. 11 is a sectional view of the inner support and conductorpositioned thereon taken along the line 11-11 of FIG. 7 with thecooperating alignment structure omitted;

FIG. 12 is a sectional view similar to FIG. 11 showing the innerconductor in rotated position after the apertures have been formed; and

FIG. 13 is a sectional View similar to FIGS. 11 and 12 showing theposition of the tubular conductor during the tab crimping operation tolock the dielectric pin in place.

With reference to FIG. 1, there is shown a coaxial transmission linehaving a tubular outer conductor 10' and a tubular inner conductor 12.Formed in the tubular inner conductor 12 are pairs of diametricallyopposed openings 14 with tabs 01' prongs 16 that are bent inwardly fromopenings 14 from a uniform compensating radius 17.

A pin 18 of a deformable dielectric material such as apolytetratluoroethylene is inserted through two diametrically opposedopenings in position so that portions 20, 22 that are equal in lengthprotrude from either side of the inner conductor 12. The spearpoints 24of two opposed tabs 16 at each opening 14 are forced into the deformabledielectric material of pin 18, so that these spearpoints project intothe dielectric material and prevent movement of pin 18 in eitherdirection so that the pin 18 is securely locked relative to the innerconductor 12. Additional pins are similarly secured to the innerconductor 12 along the length thereof at angularly oifset positions suchas in groups of three each offset 120. The assembly of dielectric pins18 on the center conductor 12 are inserted into the tubular outerconductor 10 in the position shown in FIGS. 1 and 2 and in that positionthe two inner conductors are disposed in coaxial relation with a minimalamount of dielectric material in the transmission line and theelectrical compensation required due to the dielectric support elementis provided by the aperture radii 17.

The apparatus for securing the dielectric pins '18 to the innerconductor 12 is indicated in FIGS. 4 and 5. An operating station 30 ispositioned at one end of the assembly on support 32 and a controlstation 34 is spaced at a suitable distance, such as thirty feet fromstation 30 on support 36. Intermediate supports 38 are provided asnecessary. The operating station 39 and control station 34 are connectedby three concentrically disposed coupling members 42, 44, and 46 withannular space provided between coupling members 42 and 44 in which thetubular inner conductor 12 is received.

At the operating station 30, there is positioned an alignment structure50 which includes two diametrically opposed guide channels 52, 54 and acurved support surface 56. This alignment structure is suitably securedto coupling member 42.

To component inner support 60 is secured to coupling members 44 and 46,body component 62 being secured to coupling member 44 and end component64 being secured to coupling member 46. Two crimping tools 66, 68 aresecured to the body component 62 and project axially beyond the endcomponent 64 as best indicated in FIG. 6. Each crimping tool has acrimping element 70 having a sharp point surface thereon. Formed on endcomponent '64 opposite each crimping element 70 is a cooperatingcrimping projection 72. Disposed between 'and bridging the matingsurfaces of the body component 62 and the end component 64 is a formingchannel 74 which has a smoothly curved entrance surface 76. In addition,the periphery of end component 64 is cut away at diametrically opposedpoints 7 8.

Also disposed at the operating station 30 is a piercing structuregenerally indicated in FIG. 5. This structure is mounted on a frameworksecured to the support structure 32 and includes an upstanding framemember 82 having pivotally secured thereto two arms 84, 86 which aredisposed above and below the alignment structure 50. The two arms, attheir ends opposite the pivot connections, are coupled together by asuitable operating mechanism indicated 'as a pneumatic cylinder 90having a piston rod 92, cylinder 90 being coupled to lower arm 86 andthe end of the piston rod 92 being coupled to the upper operating arm84. Pivotally connected to each operating arm 84, 86 at an intermediatepoint and in alignment with one another are two piercing pins 94, 96which are normally disposed in the guide channels 52, 54 in structure50. The arm and cylinder assembly rests on support 98.

At the control station 34, there is a second control cylinder 100 havinga piston 102 therein. The cylinder 100 is connected to both couplingmembers 42 and 44 so that they are fixed in alignment while the piston102 is connected to coupling member 46. Thus, the coupling members 42and 44 maintain the structure 50 and the body component 62 of the innersupport 60 in alignment while the end component 64 of inner support 60may be moved in an axial direction relative to the body component 62 andthe outer structure 50.

Operation of this apparatus will be best understood with reference toFIGS. 7-13 showing a series of views at operating station 30. In theposition shown in FIG. 7, the tubular inner conductor 12 is positionedbetween the outer structure 50 and the inner support structure 60. Thespacing between the two structures is such that the tube 12 can berelatively freely rotated. In the first operation, the piercing members94 and 96 are moved towards one another by control cylinder 90 to drivethem down through the wall of the inner conductor 12. It will be notedthat each piercing element 94, 96 has four flat surfaces disposed at 90to one another so that four prongs 16 tend to be formed, each having aspearpoint 24, two in line of axial direction of the conductor and twoperpendicular thereto. As the piercing elements 94, 96 are forced downthrough the metal of conductor 12, they force that metal down over thecompensation determining radius 76, providing a smooth transition fromthe cylindrical surface of the conductor 12, and then separate the metalto form the prongs 16. This piercing and prong forming operation isindicated in FIGS. 7 and 8.

After the prongs have been formed, the piercing elements 94 and 96 arewithdrawn. The end component 64 of the inner support 60 is then movedaway from the body component 62 by energization of control cylinder 100to move the piston 102 to the left as indicated in FIG. 4. Thisoperation provides sufficient space for the formed prongs 1 6 to clearthe bore walls 74 and then the conductor 12 may be rotated approximately30 relative to the m'andral structures 50, 60 to the position shown inFIG. 12. In this position, the prongs 16 are aligned with the apertures78 in the end component 64 and permit the conductor 12 to be movedaxially out (to the left as indicated in FIG. 4). The conductor is movedapproximately one inch to the position shown in FIG. 9 so that theformed apertures 14 are aligned with support 56. In this position, adielectric pin 18 is inserted through the formed openings as indicatedin FIG. 9 so that one end is seated on support 56. This support is ofuniform curvature so that as conductor 12 is rotated the pin continuesto ride on the positioning support 56 without shift in axial position.The conductor 12 is then rotated to the position shown in FIG. 13 sothat the formed prongs 16 are disposed between the crimping teeth 70 and72. The cylinder 100 is then actuated to move the piston 102 to the leftto force the crimping teeth towards one another and to crimp the prongsinto the dielectric pin 18 as indicated in FIG. 10.

After the prongs 16 have been crimped into the pin 18 so that theirspearpoints 24 are firmly embedded in the pin 18 and prevent itsmovement in either direction, the two components of the inner supportare then moved to release the crimping force and the conductor with pin'18 secured thereon may be rotated and moved axially to the desiredposition for insertion of the next dielectric support pin.

Thus, the apparatus enables the assembly of the improved dielectricsupport arrangement in a simple operation. The support arrangementemploys a minimum amount of material and appropriate electricalcompensation is automatically formed in a manner which mini mizes thereduction of the power handling capabilities of the coaxial line.

While a particular embodiment has been shown and described, variousmodifications thereof will be obvious to those skilled in the art. Forexample, the adjustability of the two components of the inner supportmay be obtained through use of a threaded interconnection between thetwo components and/or rotation of one component relative to the other.Similarly, the clinching of the prongs into the dielectric pin may beobtained by rotation of one clinching element towards another.Therefore, it is not intended that the invention be limited to thedisclosed embodiment or to details thereof and departures may be madetherefrom within the spirit and scope of the invention as defined in theclaims.

What is claimed is:

1. Apparatus for manufacturing a coaxial line support assemblycomprising a support including two axially adjustable components fordisposition inside a tubular electrical conductor;

said components having juxtaposed surfaces defining an aperture definingsurface;

and clinching means secured to each component, said clinching meansbeing disposed opposite one another for movement towards one anotherupon relative axial movement of said two components;

a cooperating alignment structure for disposition outside of saidtubular electrical conductor defining two guide channels aligned withsaid aperture defining surface of said inner support;

piercing means for movement through said guide channels and past saidaperture defining surface to pierce the metal of said tubular electricalconductor and form an aperture having a wall that has a terminal portioninside of said conductor;

means for positioning said piercing means in alignment with saidaperture defining surface;

and means to move the components of said support axially relative to oneanother.

2. Appartus for manufacturing a coaxial line support assembly comprisingan inner support including two axially adjustable components fordisposition inside a tubular electrical conductor;

said components having juxtaposed surfaces defining an aperture definingbore having a toroidal entrance surface;

and a clinching element secured to each component, said clinchingelements being disposed opposite one another for movement towards oneanother upon relative axial movement of said two components;

a cooperating alignment structure for disposition outside of saidtubular electrical conductor defining two guide channels aligned withsaid aperture defining bore;

piercing means for movement through said guide channels into saidaperture defining bore to pierce the metal of said tubular electricalconductor and form an aperture having a toroidal entrance surface thatterminates in a plurality of inwardly projecting prongs;

means for positioning said piercing means in alignment with saidaperture defining bore;

means to move the components of said inner support axially relative toone another;

and means to move said piercing means through said channels past saidaperture defining bore.

3. Apparatus for manufacturing a coaxial line support assemblycomprising an inner support including two components movable relative toone another for disposition inside a tubular electrical conductor;

said components having juxtaposed surfaces defining an aperture definingbore having a toroidal entrance surface;

and a clinching element secured to each component, said clinchingelements being disposed opposite one another for movement towards oneanother upon relative movement of said two components;

a cooperating alignment structure for disposition outside of saidtubular electrical conductor defining two guide channels aligned withsaid aperture defining bore;

piercing means for movement through said guide channels into saidaperture defining bore to pierce the metal of said tubular electricalconductor and form an aperture having a toroidal entrance surface thatterminates in a plurality of inwardly projecting prongs;

means for positioning said piercing means in alignment with saidaperture defining bore;

means to move the components of said inner support relative to oneanother to enable removal of .the prongs from said aperture definingbore after formation of the apertures;

and means to move said piercing means through said channels past saidaperture defining bore to form two aligned apertures with inwardlyprojecting prongs in said conductor when said conductor is positionedbetween said inner support and said cooperating alignment structure.

4. Apparatus for securing a dielectric support member to a tubularelectrical conductor in the manufacture of a coaxial electricaltransmission line comprising a support including two components movablerelative to one another for disposition inside a tubular electricalconductor;

said components having juxtaposed surfaces defining an aperture intowhich conductor material may be forced in an operation for forming anaperture in the wall of said conductor for receiving a dielectricsupport member;

and clinching means secured to said components, said clinching meansbeing disposed opposite one another for movement towards one another todrive conductive material surrounding the formed conductor aperture intoa dielectric support member disposed in the formed conductor aperture ina clinching operation.

No References Cited.

RICHARD H. EANES, JR., Primary Examiner.

